Alarm attachment for door-knobs



(No Model.)

T. BRADEN. ALARM ATTACHMENT TOR DOOR KNoBs.

No. 445,218. Patented Jaml 27, "1891.

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iviTn STATES PATENT innen.

THOMAS BRADEN, OF DES MOINES, IONA.

ALARM ATTACHMENT FOR DOOR-KNOBS.

SPECIFICATION forming part of Letters Patent No. 445,218, dated January 27, 1891.

Application filed May 29,1890. Serial No. 353,526. (No model.)

T0 a/ZZ. whom it may coll/cern:

Beit known that. I, THOMAS BRADEN, a cit-izen of the United States, residing at Des Moines, in the county of Polk and State of Iowa, have invented a new and useful Improvement in Alarm Attachments for Door- Knobs, the., ot' which the following is a speciiication.

My invention consists in the construction and combination of a detent orstop,a device adapted to clasp a door-hnob,a1'1d alarm mechanism witha ease or frame in such a manner that the frame and the bell and operative mechanism carried thereby will serve as a pendulum, as hereinafter set forth, pointed out in my claims, and. illustrated in the accompanying drawings, in which-d Figure l is a front elevation ol' my improved door-knob alarn'l, the cover, plate, and bell being removed to show the parts. Fig. 2 is a side view of the same, the bell being in see tion. Fig. 3 is a top sectional view on line :t Fig. i, the bell being broken away.

A represents the frame of my attachment, which is formed with an upwardly-projecting portion d.

B B are slotted spring-embracing arms, which, as shown, are secured to a pivoted portion l, with which Ithe depending' stop O is integrally formed. I do 'not desire, however, to be understood as limiting myself to the structural form of suspension shown, since the embracing-arms may be continued and formed into a loop about the knob; or I may employ wire to accomplish the same result. It will be observed that the portion h is pivoted at h to the projecting portion d of the frame A.

Referring now to the mechanism for operatingthe bell-ham mer, D D2 is a eonvolute spring of ordinary form, one end of which is secured to the shaft d, journaled within the frame, the outer end of said shaft being screwthreaded, with which the threads of a corresponding shaft d', secured to the gongE, mesh, so that the spring may be wound up by the gong.

H is a toothed wheel Afixed on the shaft d, and h is a iatchet-\vlieel, also iixed to said shaft, with which a pawl h engages, being held in engagement in one direction of revolution by the spring h, thus holding the spring D'l from unwinding. The wheel 7i engages a pinion .I on the shaft jj, journaled in the frame of the toothed wheel K, which lat ter is thus actuated by the spring when the alarm is to be sounded, being engaged bythe pawls k 7.1', formed with the rock-shaft L, also journaled within the frame. The bell-hammer D is also fixed to the said rock-shaft L, which latter has a tang M in such a position and extending in such a direction as to be engaged by the stop O when the suspending' device is in a vertical plane.

The operation of my device is as follows: The attachment maybe secured upon a doorknob by means oi the arms I5 B, which are sprung about the periphery oi the knob. In the normal position of the parts the suspending device and the actuating' mechanism and bell are in the same plane, the stop C engaging and holding the tang M, which in turn confines the rock-shaft L, the pawls k and 7.2 of which engage the toothed wheel K and hold the same from rotation against the action of the spring D?, the tendency of which latter is constantly to rotate the said wheel K. By this means the bell-hammer D remains inactive. IVhenever the door-knob is turned in either direction, the frame and the mechanism therein and the bell being pivotally connected to the suspending device remain in the same vertical plane as before, while the lower end of the stop C is turned to describe an are, which relieves the tang M and the rock-shaft- L, the pawls 7.: and 7n being also released from their engagement of the wheel K. The spring D2 rotates the said wheel, which, by means of the pawls 7c and 7o', imparts an intermittent movement to the bellhammer D, sounding the alarm. Then the door-knob springs back again into its normal positiomthe stop C again engages the tang H and causes the alarm to cease sounding.

Having thus described my invention, what I claim as new, and desire to secure by Letters of the lUnit-ed States, is-

l. In an alarm attachment for door-knobs, a case or frame adapted to support and carry a bell and striker and operative mechanism having an upward projection at its top and center, a det-ent or stop pivoted to the top of said frame, and a knob-clasping device fixed to said detent or stop, arranged and combined IOO to operate in the manner set forth, for the purposes stated.

2. An improved alarm attachment for doorknobs, consisting of a frame or case having a detent or stop pivoted to its top portion and a knob-clasping device fixed to said detenta or stop, a bell and striker, and mechanism for operating the striker, attached to and carried by said case or frame, and combined with said detent or stop, to operate in the manner set forth, for the purposes stated.

3. The frame A, having an integral projection a, the stop C, pivoted to said projection, the spring-arms B, fixed to said stop, the shafts CZ and d', and the gong; or bell E, the spring,r D2, -the toothed Wheel H, Xed to the shaft CZ, the ratchetwvheel h, xcd to the shaft d', the shaft j, having a Xed pinion or lantern Wheel J, the rock-shaft; L, carrying' the hammer D, pawls k and k', and a tang or extension M, arranged Yand combined substantially as shown and described, for the purposes specified.

THOMAS BRADEN.

Witnesses:

G. M. NAXoN, C. U. STILEs. 

